1. Field of the Invention
This invention relates to an abrasion resisting material for a sliding member, and more particularly to an abrasion resisting material for a sliding member, most suitable for an oil seal ring of a torque converter for an automatic transmission, and for a self-lubricating compressor.
2. Description of the Prior Art
Generally, an oil seal ring fitted to a shaft of aluminium alloy is made of cast iron (FC). With respect to the shaft of aluminum alloy, the abrasion resistance or wear resistance of the oil seal ring is satisfactory. However, the fittability and followability of the oil seal ring to the shaft as an associated member are unsatisfactory. That is a problem on an important oil seal ability.
In order to improve the seal ability of the oil seal ring, polytetrafluoroethylene resin (hereafter called "PTFE") containing a certain material is used as a sealing material. For example, there are a PTFE containing 20% by weight (hereafter, "by weight" is omitted) of glass fiber, a PTFE containing 60% of copper alloy (bronze), and a PTFE containing 35% of carbon graphite. Seal rings made of the above described PTFE materials have good fittability and followability to the associated surface and low frictional coefficients. Accordingly, the seal ability can be improved. For example, it is about twenty five times as high as the seal ability of the seal ring of cast iron at the earlier stage of the test time. Such PTFE materials can be applied to different sliding members.
However, the above-mentioned conventional PTFE materials have the disadvantage that they abrade abnormally much an associated material when the associated material is non-ferrous metal, and particularly aluminium or aluminium alloy. For example, when the seal ring of the conventional PTFE material is fitted to the annular groove of the shaft of aluminium alloy, the annular groove of the shaft is remarkably abraded in a driving time of less than 50 hours, and so the seal ability of the seal ring is deteriorated. There occurs some trouble in the oil pressure mechanism. As the result, the seal ring becomes unusable.
Because of such unsatisfactory suitability on abrasion resistance characteristic, the conventional PTFE material is not used as material for a seal ring to be fitted to the annular groove made in the shaft of aluminum alloy, but the seal ring of cast iron is used at present for the above described material, although its seal ability is not satisfactory.
On the other hand, when seal ability is taken seriously, it is desirable to use the seal ring of the PTFE material. However, it is undesirable that the seal ring of the PTFE material is associated with the shaft of aluminium alloy. Accordingly, it is not possible to attempt to lighten a machine by employing the shaft of aluminium alloy. Since the PTFE material is superior in seal ability, it is preferable for sealing material, but there is a problem on the suitability to material to be associated with the PTFE material. No PTFE material to solve the above problem is yet developed. Particularly, there is no material suitable to aluminium alloy or aluminium.